while 1:
    PM= float(input("请输入PM2.5的值："))
    if(PM!='Q'):
        PM=int(PM)
        if 0<=PM<=50:
            print("您当前地区空气质量状况优")
        elif 51<=PM<=100:
            print("您当前地区空气质量状况良")
        elif 101<=PM<=150:
            print("您当前地区空气质量状况轻度污染")
        elif 151<=PM<=200:
            print("您当前地区空气质量状况中度污染")
        elif 201<=PM<=300:
            print("您当前地区空气质量状况严重污染")
        elif PM>300:
            print("您当前地区空气质量状况严重污染")
        else:
            print("您当前地区不在地球上")
    else:
        break